Rushing to file your taxes as the deadline approaches can lead to last-minute mistakes.

"File it once, and then make sure you're taking some extra caution in reviewing your return," advises Jonathan Larsen, an IRS special agent.

The IRS says the most common mistakes involve bad math or typing the wrong numbers into tax software. Spelling mistakes can also lead to errors, or even just leaving off a middle initial when you've used it in years past.

The IRS will also not accept unsigned returns. Electric filings substitute a PIN for a signature.

Another common error is filing accidentally as single instead of married, which can hold up your refund.

Finally, experts say all the numbers used must match both your W2 and 1099.

"If something doesn't match, the IRS does have systems in place where they'll follow up with the taxpayer to make sure the information is accurate," Larsen says. "That will definitely delay the processing of the return."

If you do submit a mistake, you'll need to file an amended return.